1. Field of the Invention
This invention relates to an electrical fault indicator for an AC circuit.
2. Description of the Related Art
A number of types of switching devices (which includes electrical fuses), exist to provide circuit protection in case of an electrical fault. The devices are normally closed single pole, single throw, and in an overload condition open the circuit. Well-known examples are fuses and circuit breakers. A fuse may be of the cartridge type or of the screw plug type. A screw plug fuse has a visible conductive band which, in the case of an overcurrent, overheats and melts away thereby opening the circuit. The narrow band is visible under glass cover, however, due to its small size and in the low light environment in which the fuse is often found, it is often difficult to ascertain whether a particular screw plug fuse has indeed blown. Cartridge fuses are even more problematic as there is generally no external indication that the fuse has blown. Frequently, the only way to determine whether a cartridge type fuse is blown is to replace the fuse.
Accordingly, there remains a need for a quick and reliable way of determining whether a circuit protection device has open-circuited.